1. Field of the Invention
The present invention relates to a Fresnel lens sheet to be combined with a lenticular lens sheet to form a rear projection screen for a rear projection TV set, and a rear projection screen employing the Fresnel lens.
2. Description of the Related Art
A conventional rear projection screen is designed so that TV images displayed on the rear projection screen can be satisfactorily viewed by a viewer in a specific viewing region owing to the light directing characteristic of the focusing effect of a Fresnel lens sheet, the horizontal distribution of light by the sampling effect of the lenticular lens sheet, and the vertical distribution of light by the light diffusing effect of a diffusing substance contained in the rear projection screen.
Although the specific viewing region suitable for viewing pictures displayed on this conventional rear projection screen has a wide horizontal angular range, the same has a narrow vertical angular range. The vertical angular range of the viewing region can be increased by increasing the diffusing substance content of the rear projection screen to enhance the diffusing effect of the rear projection screen. However, the quantity of light traveling perpendicularly to the rear projection screen decreases and the peak screen gain of the rear projection screen is lowered if the diffusion of light is enhanced by increasing the diffusing substance content, with resultant decrease in the luminance of the rear projection screen as viewed from a viewing position on an axis perpendicular to the center of the rear projection screen.